1. Field of the Invention
This invention relates to electric devices that trigger, control, and power angle change in the slats of a window blind unit, such as a Venetian blind (mini-blind) or the like in response to changing light and/or temperature and/or manual or manual remote control signals.
2. Description of Related Prior Art
Venetian blinds, often called mini-blinds when the slats are thin, are window blind units that include a plurality of horizontally arranged parallel slats, arranged and suspended in space in a vertical stack by cords (strings) that are pivotally mounted normally over pulleys on a horizontal main shaft located above and parallel to the slats, and within a horizontal parallel housing called the head rail attached to the window frame top or header inside the building. With modern Venetian blinds, the horizontal shaft within the head rail most commonly has a worm wheel connected at one end. Arranged perpendicular and meshed to the horizontal worm wheel is a worm gear with a short shaft attached and angled approximately ninety degrees downward protruding through an opening in the head rail facing opposite the window of installation. The short protruding shaft extending from the worm gear varies in length, and its length is dependent upon the design choice of the manufacturer. Rotation of the shaft rotates the worm gear which rotates the worm wheel which in turn rotates main horizontal shaft and pulleys to move or pivot the cords supporting the slats. The cords supporting the slats are loops, one loop per pulley. At the end of the short protruding shaft, opposite the worm gear, is an eyelet (hole). The eyelet allows the connection of a plastic or wooden rod (wand) with a hook arrangement at one end that connects to the eyelet. The attached rod hangs vertically downward from the head rail. The rod allows the user to manually set the angle of the parallel slats of a typical Venetian blind window unit by grasping the rod in hand and rotating or spinning it either clockwise or counterclockwise dependant upon the direction of desired movement of the slats. Examples of Venetian blinds with horizontal slats are shown in U.S. Pat. Nos. 2,876,834; 3,809,143; and 3,559,024. As a convenience to the user, automatic control of the blind slat angle is desirable as a way to save energy through passive heating, by angling blinds closed during the night and opening during the day in winter months, and by closing temporarily during intense solar radiance appearing on the windows in summer months to save on air conditioning, and also give a lived in appearance to prevent burglaries and the obvious privacy blinds provide to the occupant of a structure.
As a result, various structures and methods of automatically controlling the angle of Venetian blinds exists. They comprise premanufactured Venetian blind units with a motor, gearbox, and position switches usually installed within the head rail. The motor and gearbox are coupled to the horizontal parallel shaft and by electronics and/or manual switches, perform the function of angling a Venetian blind window unit open or closed. The electronics comprise light and/or heat sensors and/or timers, and their associated circuits, located in the head rail or in a utility control box embedded in a wall adjacent the window Venetian blind unit, and are connected electrically to the AC line, motor, and position switches. These automatic, electrically powered, blind angling devices require labor intensive installation which makes them expensive and un-affordable to most potential users. All prior art in this area is generally directed toward what appears to be expensive installations for high rise buildings, and high priced residences. The related prior art devices are generally not structured to be inexpensive and therefore not a practical option to most potential consumers. Of the prior art devices for controlling the angle of a Venetian blind relevant to my invention, the following typify the structures, methods of use, and the problems associated therewith: A U.S. Pat. No. 4,550,759, issued to Archer Nov. 5, 1985, discloses a blind angle controlling apparatus structured to have a hand operated mechanism and simultaneously operated automatic drive. The operated automatic drive is located within the head rail at the top of the window, and the whole of the Venetian blind unit is located within the confines of two to three panes of glass. The hand operated mechanism is a rod extending from and connected via a flexible shaft and slip clutch, to the horizontal parallel shaft within the confines of the head rail, the rod itself freely hanging vertically to one end of the head rail. The structure of the Archer apparatus provides for a labor intensive installation and is designed for a multi-unit structure, such as an office building, and therefore is potentially expensive, and this precludes its use by the potential average home or apartment dweller. Potentially, the whole window would have to be replaced to accommodate the Archer apparatus, and could not be considered an economical after-market retrofit device. The Archer apparatus could not be considered transferable, by which it could be removed and transferred from one window to another window in the same structure or to a window in a completely different structure in a different location. An earlier apparatus, invented by Ringle, III, U.S. Pat. No. 4,096,903 on Jun. 27, 1978 is similar to and has similar drawbacks as the Archer apparatus.
Nortoft was granted U.S. Pat. No. 4,706,726 on Nov. 17, 1987 for the electric control of Venetian blinds. The Nortoft apparatus gives the user the ability to control angular position, by electric motorized mechanics, independently of raising or lowering the Venetian blind. The motorized mechanics of the Nortoft apparatus is built within the confines of the head rail. The control circuitry is external to the blind housing, and appears to be attached to, or embedded in the wall, electrically connected by wire cable, and its power source is supplied by household AC current. Although the motor, spring clutches, and other mechanisms are hidden within the blind housing, the cables and control circuitry must be hidden for practical design purposes, and require labor intensive effort to effect their integration into the design motif, such as running cables into the wall, and cutting a slot into the wall sheathing to accommodate the control box. This precludes the Nortoft Venetian blind unit from ever feasibly being removed from a window once installed because of the expensive labor intensive effort needed to effect removal and transfer to another window. Dimensions of windows vary widely from one structure to another and many Venetian blinds must be custom manufactured to fit the multitude of window dimensions, which precludes the Nortoft Venetian blind apparatus from any practical transfer to another window in another structure, once installed.
Osaka and Sagawa were granted U.S. Pat. No. 4,664,169 on May 12, 1987 for a Venetian blind apparatus comprising a plurality of spaced parallel slats, called louvers by the inventors, and secured for rotation about parallel axes and is centered within two light transparent walls of the housing. The louvers are tilt angled open or closed by the mechanical action of a ceramic piezoelectric bimorph, when powered by a direct current source, such as a solar charged battery or other direct current source. In addition a motor and gearbox are installed in the head rail to accommodate vertical raising or lowering of the Venetian blind. Although it is claimed that the bimorph mechanism is an economical method for tilt angling the louvers/slats, one problem with the bimorph mechanism is that it will only tilt angle the slats/louvers in one direction of orientation. Another problem which increases cost is that the bimorph mechanism must be manufactured longer or shorter, and be powered with more or less current to accommodate the mechanical power output needed to tilt angle a larger or smaller Venetian blind. The dimensions of the Osaka and Sagawa Venetian blind apparatus once manufactured, are static to a particular sized window and can not feasibly be resized or transferred unless the new window dimensions are equivalent and then the whole Venetian blind apparatus, including housing, head rail, slats, cords, etc. must be transferred. In addition, the Osaka and Sagawa Venetian blind apparatus requires special materials, more expensive than conventional materials used in comparable blind apparatus. There is no mention of location of a switch or electronics for triggering the bimorph mechanism, only that it can be controlled by a switch. It must be assumed that the control switch would be placed in a convenient location for the user, most likely in the wall or window sill precluding the Osaka and Sagawa Venetian blind apparatus from a convenient, and inexpensive transferal to another window.
Long and Shelton were granted U.S. Pat. No. 4,979,550 on Dec. 25, 1990 for a window blind control apparatus that allows for selective control in the angling function of opening or closing a Venetian blind window unit or the like. Selective control includes a photo-electric cell, a radio frequency controller, a manually displaceable slide switch, or a manually rotatable control rod, to perform the previously mentioned functions. Although the Long and Shelton device appears to be structured so the device could be transferable to various Venetian blind units of different sizes, no claim is made for this convenience of use. The problem with their apparatus is that the physical structure is box shaped and must be attached with machine screws to the adjacent wall next to the input shaft on the head rail. And further the photo-cell for light detection is attached to the adjacent window sill via an obtrusive wire cord running to the box shaped apparatus containing the motor and associated circuitry. The apparatus as depicted by Long and Shelton would be objected to by many consumers because it is obtrusive and does not fit well into the Venetian blind motif as the original angling rod. The window blind unit would need an accompanying Valence to help hide the obtrusive apparatus, and still could be seen by individuals close to the window. Long and Shelton make reference to U.S. Pat. No. 4,492,908 for circuitry in conjunction with photo-electrics of controlling the blind angle. This circuitry could be powered by batteries, but only for a very short time before replacement or recharge would be needed. Therefore, an outside power source, such as AC power, or solar, would be needed in combination with the Long and Shelton apparatus to be convenient to the user and would require expensive, labor intensive, unsightly if not hidden, power cabling, or solar array installation.